"Now that you know that there are three fans in this thing you
are probably thinking: "Man! That must be loud!" So that is why we
have a little switch located on the back of the PSU (rear of the case)
with three settings, auto, middle, and low. On auto the fans will
adjust to whatever speed they need for better cooling, this is the
more quiet setting you can select, then there is the low, fans run at
higher RPM than auto, still not loud at all, then there is the third
setting: middle, fans run at their highest speed, moving a lot of air,
still very low noise levels."